Surgical scissors are commonly used in many surgical procedures for cutting tissue that is vascularized, i.e., contains blood or other vessels. The resultant bleeding or other fluid loss that occurs is not only of concern from the standpoint of fluid loss, but blood may also obscure the surgical field or site. Controlling such fluid loss and bleeding has, in the past, required significant time and attention of the surgeon during many surgical procedures.
Scissors that use radiofrequency (RF) energy in a manner such that the tissue is heated as it is cut, thus promoting immediate hemostasis, have been used for many years to control such bleeding or other fluid loss. Early electrosurgical scissors used monopolar RF power, where the scissors constituted one electrode and the patient rested on the other electrode (which was typically in the form of a conductive mat) to complete the circuit. Current flowed generally through the patient between the electrodes due to the voltage applied across the electrodes by an RF power supply. The uncertainty of the path of current flow through the body and possible unintentional harm to other tissues, however, encouraged the further development in electrosurgical scissors.
Recently, efforts have been made to develop electrosurgical scissors, as illustrated, for example, in U.S. Pat. Nos. 5,324,289 and 5,330,471, in which one blade includes one electrode and the other blade includes or functions as the other electrode, so that current flows between the blades as they cut the desired tissue.
More recently, electrosurgical scissors have been provided in which each cutting blade itself includes two electrodes for connection to a RF energy power supply. The tissue contacting surfaces of at least one, and preferably both, blades include two spaced-apart electrodes which extend along the tissue contacting surface and are connectable to a voltage source for applying a voltage between the electrodes of each blade. As a result, current flows between the first and second electrodes of each blade to promote hemostasis in the tissue as the blade is moved into contact with the tissue, such as during the cutting action. Such scissors are disclosed in the co-pending applications Ser. No. 399,421 filed Mar. 7, 1995 and Ser. No. 593,148, filed Feb. 21, 1996, which are herein incorporated by reference. Another example of electrosurgical scissors is also disclosed in U.S. Pat. No. 5,540,685.
Although electrosurgical scissors have generally performed well in promoting hemostasis, need for further improvement to enhance their long term use has become evident. Specifically, the cutting edges of the scissor blades typically dull after repeated use, and require resharpening. The presence of one or more electrodes and insulators on a blade, however, significantly complicates and increases the expense and/or time for resharpening of the scissors blades. Further, as with all reusable medical instruments, there is a need to provide for easy re-sterilization of the instrument between uses. The presence of an electrode and insulation structure on the blade or blades can make thorough cleaning and sterilization more tedious and time consuming. Finally, repeated use of steam sterilization can result in undesirable wear or breakdown of the electrodes and their associated insulating material, necessitating more frequent replacement than might otherwise be required for standard, non-electrosurgical scissors.
Accordingly, there is a continuing need for electrosurgical scissors which are reusable, more easily resharpened and resterilized, and providing longer product life.